package com.designpattern.softwaredesignpatternstudy.principle;

import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

/**
 * @Author: Jiangxx
 * @Date: 2021/11/02
 * @Description:
 */
public class Calculator {

    public static void main(String[] args) {
        String expression = "100+4*(30-100/5)";
        List<String> InfixExpressionList =toInfixExpressionList(expression);
        System.out.println(InfixExpressionList);
        List<String> SuffixExpressionList = parseSuffixExpressionList(InfixExpressionList);
        System.out.println(SuffixExpressionList);
        System.out.println("运行结果为"+calculate(SuffixExpressionList));
    }

    public static List<String> parseSuffixExpressionList(List<String> ls){
        Stack<String> s1 = new Stack<>();
        List<String> s2 = new ArrayList<>();

        //遍历
        for(String item : ls) {
            if(item.matches("\\d+")) {
                s2.add(item);
            }else if(item.equals("(")) {
                s1.push(item);
            }else if(item.equals(")")) {
                while(!s1.peek().equals("(")) {
                    s2.add(s1.pop());
                }
                s1.pop();
            }else {
                while(s1.size() != 0 && Operation.getValue(s1.peek()) >= Operation.getValue(item)) {
                    s2.add(s1.pop());
                }
                s1.push(item);
            }
        }

        while(s1.size() != 0) {
            s2.add(s1.pop());
        }

        return s2;

    }

    /**
     * 将中缀表达式转成对应的list
     */
    public static List<String> toInfixExpressionList(String s){
        List<String> ls = new ArrayList<String>();
        int i = 0;
        String str;
        char c;
        do {
            if((c=s.charAt(i)) < 48 || (c=s.charAt(i)) > 57){
                ls.add(""+c);
                i++;
            }else {
                str="";
                while(i < s.length() && (c=s.charAt(i)) >=48 && (c=s.charAt(i)) <= 57) {
                    str += c;
                    i++;
                }
                ls.add(str);
            }
        }while(i < s.length());
        return ls;
    }

    public static int calculate(List<String> ls) {
        Stack<String> stack = new Stack<>();
        for(String item :ls) {
            if(item.matches("\\d+")) {
                stack.push(item);
            }else {
                int num2 = Integer.parseInt(stack.pop());
                int num1 = Integer.parseInt(stack.pop());
                int res = 0;
                if(item.equals("+")) {
                    res = num1 + num2;
                }else if(item.equals("-")){
                    res = num1 - num2;
                }else if(item.equals("*")) {
                    res =num1 *num2;
                }else if(item.equals("/")){
                    res = num1 / num2;
                }else {
                    throw new RuntimeException("运算有误");
                }
                stack.push(""+res);

            }
        }
        return Integer.parseInt(stack.pop());
    }
}

class Operation{
    private static int ADD = 1;
    private static int SUB = 1;
    private static int MUL = 2;
    private static int DIV = 2;

    public static int getValue(String operation) {
        int result = 0;
        switch (operation) {
            case "+":
                result = ADD;
                break;
            case "-":
                result = SUB;
                break;
            case "*":
                result = MUL;
                break;
            case "/":
                result = DIV;
                break;
            default:
                System.out.println("不存在该运算符");
                break;
        }
        return result;
    }
}
